Printing apparatus, control method of printing apparatus and storage medium

ABSTRACT

A printing apparatus conveys a printing medium in a first direction, and includes an encoder that outputs a predetermined signal in accordance with a conveyance amount of the printing medium in the first direction, and a print head having a plurality of nozzle rows, each of which includes a plurality of nozzles ejecting ink, arrayed in a second direction intersecting with the first direction. In addition, a print engine is connected with the print head and performs conversion processing from image data into print data. The print engine has a first buffer storing the image data, has a second buffer storing the print data, and converts image data stored in the first buffer into print data in response to a first interrupt signal based on the predetermined signal output from the encoder, and stores the print data in the second buffer.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a printing apparatus that prints animage on a printing sheet, a control method of a printing apparatus, anda storage medium.

Description of the Related Art

Conventionally, the ink jet printing apparatus is prevailing in the wideindustrial field as a printing unit that is comparatively simple andexcellent and for the ink jet printing apparatus, an increase in theprinting speed, an improvement in image quality, and so on arerequested.

Then, as one measure to respond to the request for an increase in theprinting speed, an ink jet printing apparatus including a line head inwhich nozzle rows are arranged perpendicular to the conveyance directionof a printing sheet and having the same length as the width of theprinting sheet is adopted.

Further, in the ink jet printing apparatus including the line head suchas this, aiming at transmission of print data at a high speed andaccurately, a method of controlling a buffer that stores print data hasbeen proposed (Japanese Patent Laid-Open No. 2017-132175). In thismethod, a head controller allocated to each of a plurality of printheads is caused to include a buffer corresponding to each nozzle row andhaving a read pointer and by the head controller, the position of thepointer is managed and a transfer request to a high-order controller iscontrolled.

However, the method in which the head controller manages the position ofthe read pointer in the buffer provided for each nozzle row of the printhead has such a problem that control becomes complicated because as thenumber of nozzle rows increases, the number of management-targetpointers increases.

SUMMARY OF THE INVENTION

The present invention has been made in view of the conventional problemdescribed above and an object is to provide an image forming apparatuscapable of simple buffer control in a printing apparatus including aplurality of nozzle rows.

In order to attain the above-described object, the present invention isa printing apparatus including: a conveyance unit configured to convey aprinting medium; an encoder that outputs a predetermined signal inaccordance with a drive amount of the conveyance unit; a print head inwhich a plurality of nozzle rows in which a plurality of nozzlesejecting ink is arrayed is arrayed in a direction intersecting with aconveyance direction of the printing medium; and a print engineconnected with the print head and performing conversion processing fromimage data into print data, and the print engine: has a first bufferstoring the image data; has a second buffer storing the print data; andconverts image data stored in the first buffer into print data inresponse to a first interrupt signal based on the predetermined signaloutput from the encoder, and stores the print data in the second buffer.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an internal configuration diagram of an ink jet printingapparatus;

FIG. 2 is a block diagram showing a control configuration of theprinting apparatus;

FIG. 3 is a diagram showing a signal output by a rotary encoder;

FIG. 4 is a block diagram showing a configuration of an encoder signalprocessing unit;

FIG. 5 is a diagram showing a head transfer permit signal and a headtransfer trigger signal;

FIG. 6 is a diagram showing an image that is taken as a target ofprinting processing;

FIG. 7 is a diagram showing a configuration of a first buffer;

FIG. 8 is a diagram showing a configuration of a second buffer;

FIG. 9 is a timing chart showing a state of processing before aconveyance operation of a printing sheet;

FIG. 10 is a timing chart showing a state of processing at the time ofthe conveyance operation of a printing sheet;

FIG. 11 is a flowchart showing a procedure of transfer processing ofimage data before the conveyance operation of a printing sheet;

FIG. 12 is a flowchart showing a procedure of image processing beforethe conveyance operation of a printing medium;

FIG. 13 is a flowchart showing a procedure of transfer processing ofimage data at the time of the conveyance operation of a printing sheet;

FIG. 14 is a flowchart showing a procedure of processing at the time ofthe conveyance operation of a printing sheet; and

FIG. 15 is a diagram showing a position relationship between a printhead and image data that is printed on a printing medium.

DESCRIPTION OF THE EMBODIMENTS

In the following, with reference to the drawings, a printing apparatusaccording to embodiments of the present invention is explained. Thefollowing embodiments are not intended to limit the present inventionand all combinations of features explained in the present embodimentsare not necessarily indispensable to the solution of the presentinvention.

FIG. 1 is an internal configuration diagram of an ink jet printingapparatus 1 (hereinafter, printing apparatus 1). In FIG. 1, thex-direction indicates the horizontal direction, the y-direction(direction perpendicular to the paper surface) indicates the directionin which ejection ports are arrayed in a print head 8, to be describedlater, and the z-direction indicates the vertical direction,respectively.

The printing apparatus 1 is a multi function printer including a printunit 2 and a scanner unit 3 and capable of performing a variety of kindsof processing relating to the printing operation and the readingoperation by the print unit 2 and the scanner unit 3 individually, or inan interlocking manner of the print unit 2 and the scanner unit 3. Thescanner unit 3 includes an ADF (Auto Document Feeder) and an FBS (FlatBed Scanner) and is capable of reading a document automatically fed bythe ADF and reading (scanning) a document placed on a document table ofthe FBS by a user. Here, the multi function printer is one having boththe print unit 2 and the scanner unit 3, but the multi function printermay be an aspect in which the scanner unit 3 is not included. FIG. 1shows a case where the printing apparatus 1 is in a standby state wherethe printing apparatus 1 is performing neither the printing operationnor the reading operation.

In the print unit 2, at the bottom in the vertically downward directionof a casing 4, a first cassette 5A and a second cassette 5B for storinga printing medium (cut sheet) S are installed in an attachable anddetachable manner. In the first cassette 5A, comparatively smallprinting media up to the A4 size, and in the second cassette 5B,comparatively large printing media up to the A3 size are stored in apiled-up manner. In the vicinity of the first cassette 5A, a first feedunit 6A for feeding stored printing media by separating one by one isprovided. Similarly, in the vicinity of the second cassette 5B, a secondfeed unit 6B is provided. In a case where the printing operation isperformed, the printing medium S is selectively fed from one of thecassettes.

A conveyance roller 7, a discharge roller 12, a pinch roller 7 a, a spur7 b, a guide 18, an inner guide 19, and a flapper 11 are conveyancemechanisms for guiding the printing medium S in a predetermineddirection. The conveyance roller 7 is arranged on the upstream side andon the downstream side of the print head 8 and is a drive roller that isdriven by a conveyance motor, not shown schematically. The pinch roller7 a is a follower roller that nips and rotates the printing medium Stogether with the conveyance roller 7. The discharge roller 12 isarranged on the downstream side of the conveyance roller 7 and is adrive roller that is driven by a conveyance motor, not shownschematically. The spur 7 b sandwiches and conveys the printing medium Stogether with the conveyance roller 7 arranged on the downstream side ofthe print head 8 and the discharge roller 12.

The guide 18 is provided in the conveyance path of the printing medium Sand guides the printing medium S in a predetermined direction. The innerguide 19 is a member extending in the y-direction and has a curved sidesurface, and guides the printing medium S along the side surface. Theflapper 11 is a member for switching directions in which the printingmedium S is conveyed at the time of the both-side printing operation. Adischarge tray 13 is a tray for loading and holding the printing mediumS for which the printing operation has been completed and which isdischarged by the discharge roller 12.

The print head 8 is a color ink jet print head of line head type and inwhich a plurality of ejection ports from which ink is ejected inaccordance with print data is arrayed along the y-direction (that is,the direction intersecting with the conveyance direction of the printingmedium S) so as to correspond to the width of the printing medium S. Aplaten 9 is configured by a flat plate extending in the y-direction andsupports the printing medium S from the rear side, for which theprinting operation is performed by the print head 8.

An ink tank unit 14 stores four color inks to be supplied to the printhead 8, respectively. Here, the four color inks refer to inks of cyan(C), magenta (M), yellow (Y), and black (K). An ink supply unit 15 isprovided on the way in the flow path connecting the ink tank unit 14 andthe print head 8 and adjusts the pressure and the amount of flow of theink within the print head 8 to an appropriate range. The printingapparatus 1 has a circulation-type ink supply system and the ink supplyunit 15 adjusts the pressure of the ink supplied to the print head 8 andthe amount of flow of the ink recovered from the print head 8 to anappropriate range. A maintenance unit 16 includes a cap unit 10 and awiping unit 17 and performs the maintenance operation for the print head8 by causing these units to operate at predetermined timing.

FIG. 2 is a block diagram showing a control configuration in theprinting apparatus 1. The printing apparatus 1 mainly includes a printengine unit 200 configured to centralizedly control the print unit 2, ascanner engine unit 300 configured to centralizedly control the scannerunit 3, and a controller unit 100 configured to centralizedly controlthe entire printing apparatus 1. A print controller 202 controls variousmechanisms of the print engine unit 200 in accordance with instructionsof a main controller 101 of the controller unit 100. Various mechanismsof the scanner engine unit 300 are controlled by the main controller 101of the controller unit 100. In the following, details of the controlconfiguration are explained.

In the controller unit 100, the main controller 101 including a CPUcontrols the entire printing apparatus 1 by using a RAM 106 as a workarea in accordance with programs and various parameters stored in a ROM107. For example, in a case where a print job is input from a hostapparatus 400 via a host I/F (interface) 102 or a wireless I/F 103, animage processing unit 108 performs predetermined image processing forthe received image data in accordance with instructions of the maincontroller 101. The predetermined image processing performed in theimage processing unit 108 includes binarization processing to convertmultivalued image data into binary image data. Then, the main controller101 transmits the image data for which the image processing has beenperformed to the print engine unit 200 via a print engine I/F 105.Further, the main controller 101 transmits each command for givinginstructions to the print controller 202 to the print engine unit 200separate from the image data via the print engine I/F 105.

The printing apparatus 1 may acquire image data from the host apparatus400 via wireless communication or wired communication or may acquireimage data from an external storage device (USB memory and the like)connected to the printing apparatus 1. However, the communication methodthat is made use of for wireless communication or wired communication isnot limited to this. For example, as the communication method that ismade use of for wireless communication, it is possible to apply Wi-Fi(Wireless Fidelity) (registered trademark) and Bluetooth (registeredtrademark). Further, as the communication method that is made use of forwired communication, it is possible to apply USB (Universal Serial Bus)and the like. In addition, for example, in a case where a read commandis input from the host apparatus 400, the main controller 101 transmitsthis command to the scanner unit 3 via a scanner engine I/F 109.

An operation panel 104 is a mechanism for a user to input and output forthe printing apparatus 1. It is possible for a user to give instructionsas to the operation, such as copying and scanning, to set a printingmode, to recognize information on the printing apparatus 1, and so onvia the operation panel 104.

In the print engine unit 200, the print controller 202 including a CPUcontrols various mechanisms included in the print unit 2 by using a RAM204 as a work area in accordance with programs and various parametersstored in a ROM 203.

A controller I/F 201 performs transmission and reception of variouscommands and communication of image data with the print engine I/F 105.In a case of receiving various commands and image data via thecontroller I/F 201, the print controller 202 temporarily stores them inthe RAM 204. An image processing controller 205 converts the image datasaved in the RAM 204 into print data in accordance with instructions ofthe print controller 202 so that the print head 8 can make use of forthe printing operation. In a case of performing the processing toconvert image data into print data (conversion processing), the imageprocessing controller 205 further outputs an interrupt signal (imageprocessing completion interrupt signal) indicating that the conversionprocessing is completed to the print controller 202. The conversionprocessing from image data into print data performed in the imageprocessing controller 205 includes smoothing processing.

In the following, explanation is given by taking the buffer within theRAM 204, which stores image data received from the print controller 202,as a first buffer and the buffer within the RAM 204, which stores printdata converted by the image processing controller 205, as a secondbuffer.

Then, at the time of performing the printing operation after this, theprint controller 202 conveys the printing medium S by driving the feedunits 6A and 6B, the conveyance roller 7, the discharge roller 12, andthe flapper 11 shown in FIG. 1 via a conveyance control unit 207.

To the axis of a conveyance motor 20 that drives the conveyance roller7, a rotary encoder 21 is attached. The rotary encoder 21 is, forexample, an optical rotary encoder and provided to detect the conveyanceamount of the printing medium S in accordance with the drive amount ofthe conveyance motor 20. In a case where the conveyance motor 20 rotatesa predetermined amount, the rotary encoder 21 outputs a predeterminedsignal. Specifically, as shown in FIG. 3, the rotary encoder 21 outputsan A-phase signal and a B-phase signal in accordance with the driveamount (eventually corresponding to the conveyance amount of theprinting medium S) of the conveyance motor 20. As a supplement, theB-phase signal is in a phase relationship in which the phase of theB-phase signal is delayed from that of the A-phase signal by 90 degreesand used for determining (checking) the rotation direction of the rotaryencoder 21.

The A-phase signal and the B-phase signal output from the rotary encoderare input to an encoder signal processing unit 1000 of the conveyancecontrol unit 207. In more detail, the encoder signal processing unit1000 includes a head transfer timing signal generation unit 1001 and aposition counter 1002 and the A-phase signal and the B-phase signal areinput to the head transfer timing signal generation unit 1001 and theposition counter 1002, respectively, as shown in FIG. 4.

The position counter 1002 monitors the A-phase signal and increments aposition counter value for each rise edge of the A-phase signal. Theposition counter 1002 includes a register to which it is possible forthe print controller 202 to set a predetermined value and in a casewhere the incremented position counter value becomes equal to apredetermined value set to the register, the position counter 1002outputs a position counter interrupt signal to the print controller 202.In addition, the position counter 1002 outputs the position countervalue to the head transfer timing signal generation unit 1001.

The head transfer timing signal generation unit 1001 outputs a headtransfer permit signal and a head transfer trigger signal as shown inFIG. 5 to a head I/F 206 based on the input A-phase signal and B-phasesignal and the position counter value.

In a case where the head transfer trigger signal becomes the High levelin the state where the head transfer permit signal is at the High level,the head I/F 206 transfers print data corresponding to one line to theprint head 8. In FIG. 5, the head transfer trigger signal has become theHigh level 24 times in the state where the head transfer permit signalis at the High level, and therefore, the head I/F 206 has read the printdata corresponding to a total of 24 lines from the RAM 204 andtransferred to the print head 8.

In the present embodiment, the position counter 1002 increments theposition counter value for each rise edge of the A-phase signal, but thetiming of increment may be for each fall edge of the A-phase signal.Further, the signal (target) that is monitored at the time of incrementfor each edge may be the B-phase signal. Here, a case is shown where theprint engine unit 200 includes the one image processing controller (CPU)205, the one ROM 203, and the one RAM 204. However, the numbers of imageprocessing controllers (CPUs), ROMs, and RAMs included in the printengine unit 200 are not limited to one, respectively, and may be two ormore.

A head carriage control unit 208 changes the orientation and position ofthe print head 8 in accordance with the operating state, such as themaintenance state and the printing state of the printing apparatus 1. Anink supply control unit 209 controls the ink supply unit 15 so that thepressure of the ink to be supplied to the print head 8 is adjustedwithin an appropriate range. A maintenance control unit 210 controls theoperation of the cap unit 10 and the wiping unit 17 in the maintenanceunit 16 at the time of performing the maintenance operation for theprint head 8.

In the scanner engine unit 300, the main controller 101 controlshardware resources of a scanner controller 302 by using the RAM 106 as awork area in accordance with programs and various parameters stored inthe ROM 107. Due to this, various mechanisms included in the scannerunit 3 are controlled. For example, by the main controller 101controlling the hardware resources within the scanner controller 302 viaa controller I/F 301, a document mounted on the ADF by a user isconveyed via a conveyance control unit 304 and read by a sensor 305.Then, the scanner controller 302 saves the read image data in a RAM 303.It is possible for the print controller 202 to cause the print head 8 toperform the printing operation based on the image data read by thescanner controller 302 by converting the image data acquired asdescribed above into print data.

In the following, based on the configuration described above, by usingFIG. 6 to FIG. 8, the configuration of the buffers (the first bufferthat stores image data and the second buffer that stores print data)within the RAM 204 is explained, and further, by using FIG. 9 to FIG.15, the specific processing in the printing apparatus 1 is explained.FIG. 6 is an image corresponding to one page that is the target ofprinting processing in the printing apparatus 1. In FIG. 6, printing ofthe image is planned and in accordance with the printing order of theimage (that is, the conveyance direction of the printing sheet), theimage is equally divided into eight areas, that is, an area (1) to anarea (8) in the order from the upstream side in the conveyancedirection.

FIG. 7 is a diagram showing the configuration of the first buffer thatstores image data received from the main controller 101 described above.The first buffer is configured within the RAM 204 as described above.

As shown in FIG. 7, the first buffer includes two storage areas eachstoring one of the eight areas obtained by equally dividing the image(that is, area corresponding to one eighth of the image). Hereinafter,one of the storage areas is referred to as a storage area A and theother storage area is referred to as a storage area B. Further, as shownin FIG. 7, in the printing apparatus 1, in the process of performingimage processing, of the areas shown in FIG. 6, the areas (1), (3), (5),and (7) are temporarily stored in the storage area A and the areas (2),(4), (6), and (8) are temporarily stored in the storage area B. As asupplement, the control method of the first buffer will be describedlater by using FIG. 11 and FIG. 13.

FIG. 8 is a diagram showing the configuration of the second buffer thatstores the print data converted by the image processing controller 205described above. The second buffer is configured within the RAM 204 asdescribed above.

As shown in FIG. 8, the second buffer includes four storage areas eachstoring one of the eight areas obtained by equally dividing the image.Hereinafter, a first storage area of the four storage areas is referredto as a storage area K, a second storage area is referred to as astorage area L, a third storage area is referred to as a storage area M,and a fourth storage area is referred to as a storage area N. Further,in the printing apparatus 1, in the process of generating print data, ofthe areas shown in FIG. 6, the areas (1) and (5) are stored temporarilyin the storage area K, the areas (2) and (6) are stored temporarily inthe storage area L, the areas (3) and (7) are stored temporarily in thestorage area M, and the areas (4) and (8) are stored temporarily in thestorage area N. As a supplement, the control method of the second bufferwill be described later by using FIG. 12 and FIG. 14.

Next, as the specific processing of the printing apparatus 1, by usingFIG. 9, FIG. 11, and FIG. 12, transfer processing of image data andimage processing before the conveyance operation of a printing sheet areexplained. Further, by using FIG. 10, FIG. 13, FIG. 14, and FIG. 15,transfer processing of image data, image processing, and transferprocessing of print data at the time of the conveyance operation of aprinting sheet are explained.

FIG. 9 is a timing chart showing the head transfer permit signal, thestate of head transfer, the image processing by the image processingcontroller 205, and the state of data transfer from the controller unit100 to the print engine unit 200 before the conveyance operation of aprinting sheet.

As describe above, FIG. 9 shows the state of processing before theconveyance operation of a printing sheet (that is, before execution ofthe printing processing) as a timing chart, and therefore, the headtransfer permit signal is kept in the state of the Low level and headtransfer of print data is not performed. On the other hand, datatransfer (hereinafter, processing 1) from the controller unit 100 to theprint engine unit 200 and image processing (hereinafter, processing 2)by the image processing controller 205 are performed until all thestorage areas of the first buffer and the second buffer are filledfully. Specifically, in this case, the processing is performed until theimage data of the area (5) is stored in the storage area A and the imagedata of the area (6) is stored in the storage area B of the firstbuffer, and the area (1) is stored in the area K, the area (2) is storedin the area L, the area (3) is stored in the area M, and the area (4) isstored in the area N of the second buffer.

In the following, in accordance with the timing chart in FIG. 9,processing 1 and processing 2 are explained. First, processing 1 isperformed for the area (1) of the image. Then, after processing 1 forthe area (1) is completed, that is, in a case where the image data ofthe area (1) is stored in the storage area A of the first buffer,processing 2 for the area (1) is performed.

Further, at the same time, the storage area B of the first buffer isempty, and therefore, processing 1 for the area (2) is performed andimage data is stored in the storage area B. Then, after processing 2 forthe area (1) is completed, the image processing controller 205 outputsan image processing completion interrupt signal to the print controller202. The print controller 202 having received the image processingcompletion interrupt signal further notifies the main controller 101that processing 2 is completed.

The main controller 101 performs processing 1 for the area (3) becausean empty area is produced in the storage area A of the first buffer inresponse to the completion of processing 2 for the preceding area (1)and stores image data in the storage area A. Further, the imageprocessing controller 205 performs processing 2 for the area (2) becauseprocessing 1 for the area (2) is also already completed at the point intime at which processing 1 for the area (3) is started.

The series of processing is performed similarly also in the subsequentareas until all the storage areas of the first buffer and the secondbuffer are filled fully. That is, as described above, the series ofprocessing is performed until that state is brought about where theareas (5) and (6) of the image are stored in the first buffer and theareas (1) to (4) of the image are stored in the second buffer.

FIG. 11 is a flowchart showing a procedure of the data transferprocessing from the controller unit 100 to the print engine unit 200before the conveyance operation of a printing sheet. Specifically, aflowchart showing a procedure of processing 1 for the areas (1) to (6)described above before the conveyance operation of a printing sheet.

At step S1101, the main controller 101 determines whether or not thereis an empty area in the first buffer within the RAM 204. In a case ofdetermining that there is not an empty area in the first buffer (No atS1101), the main controller 101 stands by until an empty area isproduced in the first buffer. On the other hand, in a case ofdetermining that there is an empty area in the buffer (Yes at S1101),the main controller 101 advances the processing to step S1102.

At step S1102, the main controller 101 transfers the image datacorresponding to one of the eight areas obtained by equally dividing theimage from the controller unit 100 to the print engine unit 200. Thatis, the main controller 101 performs processing 1. At step S1102, eachtime the processing at steps S1101 to S1104 is performed, the area isshifted to the downstream side in the conveyance direction (that is, thearea is changed from the area (1) to the area (2), from the area (2) tothe area (3)) and processing 1 is performed in order from the area (1).

At step S1103, the main controller 101 determines whether or not thetransfer of the image data transferred from the controller unit 100 atstep S1120 to the print engine unit 200 is completed. That is, the maincontroller 101 determines whether or not processing 1 is completed. In acase of determining that processing 1 is not completed (No at S1103),the main controller 101 stands by until processing 1 is completed. Onthe other hand, in a case of determining that processing 1 is completed(Yes at S1103), the main controller 101 advances the processing to stepS1104.

At step S1104, the main controller 101 determines whether or notprocessing 1 is completed for the areas (1) to (6) of the image. Then,in a case of determining that processing 1 for all the areas (1) to (6)of the image is not completed yet (No ate S1104), the main controllerreturns the processing to step S1101 after shifting the area to thedownstream side in the conveyance direction as described above. On theother hand, in a case of determining that processing 1 for all the areas(1) to (6) of the image is completed (Yes at S1104), the main controller101 terminates the processing shown in FIG. 11.

FIG. 12 is a flowchart showing a procedure for causing the imageprocessing controller 205 to perform image processing before theconveyance operation of a printing sheet. Specifically, a flowchartshowing a procedure of processing 2 for (1) to (4) described abovebefore the conveyance operation of a printing sheet.

At step S1201, the print controller 202 determines whether or not thestate is a state where all the storage areas of the second buffer arefilled fully. In a case of determining that the state is not a statewhere all the storage areas of the second buffer are filled fully (No atS1201), the print controller 202 advances the processing to step S1202.

At step S1202, the print controller 202 performs various kinds ofsetting of, for example, such as an image processing parameter and a DMAaddress, for the image processing controller 205. Regarding step S1202,in a case where the processing is performed for the area (1), afterthis, it is not necessarily required to perform the processing, and itis sufficient to perform the processing appropriately in accordance witha change in environment or the like.

At step S1203, the print controller 202 determines whether or not imagedata is stored in the first buffer within the RAM 204. In a case ofdetermining that image data is not stored in the first buffer (No atS1203), the print controller 202 stands by until image data is stored inthe first buffer. On the other hand, in a case of determining that imagedata is stored in the first buffer (Yes at S1203), the print controller202 advances the processing to step S1204.

At step S1204, the print controller 202 boots the image processingcontroller 205 and causes the image processing controller 205 to startimage processing. That is, the print controller 202 causes the imageprocessing controller 205 to start processing 2.

After causing the image processing controller 205 to start processing 2,at step S1205, the print controller 202 determines whether or not aninterrupt signal relating to image processing completion accompanyingthe completion of processing 2 is received. In a case of determiningthat the interrupt signal relating to image processing completion is notreceived at step S1205 (No at S1205), the print controller 202 stands byuntil the interrupt signal is received. On the other hand, in a case ofdetermining that the interrupt signal relating to image processingcompletion is received (Yes at S1205), the print controller 202 advancesthe processing to step S1206.

At step S1206, the print controller 202 performs clear processing of thereceived interrupt signal. After performing the processing at stepS1206, the print controller 202 shifts the area to the downstream sidein the conveyance direction (that is, for example, the area is changedfrom the area (1) to the area (2), from the area (2) to the area (3),and so on) and returns the processing to step S1201. After this, at stepS1201, in a case where all the storage areas of the second buffer arefilled fully (Yes at S1201), it is determined that the image processingin the areas (1) to (4) of the image (that is, generation of print data)is completed and the processing shown in FIG. 12 is terminated.

Next, transfer processing of image data, image processing, and transferprocessing of print data (head transfer processing) at the time of theconveyance operation of a printing sheet are explained. FIG. 10 is atiming chart showing the head transfer permit signal, the state of headtransfer, the image processing by the image processing controller 205,and the state of data transfer from the controller unit 100 to the printengine unit 200 at the time of the conveyance operation of a printingsheet.

As described above, FIG. 10 shows the state of the processing at thetime of the conveyance operation of a printing sheet (that is, the statewhere printing processing is performed while conveying a printing sheet)as a timing chart and further, the processing is shown as processingthat follows the processing shown in FIG. 9.

As shown in FIG. 10, the head transfer permit signal becomes the Highlevel at the position at which the printing operation is started. In acase where the head transfer trigger signal becomes the High level inthe state where the head transfer permit signal is kept at the Highlevel, the head I/F 206 reads the print data from the storage area inwhich the area (1) of the image is stored of the second buffer andtransfers the print data to the print head 8. That is, in accordancewith the level of a predetermined transfer signal, the head I/F 206reads the print data from the storage area K and transfers the printdata to the print head 8.

The head transfer trigger signal is the signal shown in FIG. 5 describedabove (that is, the signal output from the head transfer timing signalgeneration unit 1001 based on the position counter value input from theposition counter 1002) and is not shown schematically in FIG. 10.Further, in the position counter 1002, a value corresponding to theposition corresponding to one eighth in the conveyance direction fromthe front end of the image is set in advance as the position counterinterrupt value. Consequently, in a case where the printing sheet isconveyed up to the position (that is, in a case where the positioncounter value corresponding to the conveyance amount corresponding toone eighth of the image is reached), a position counter interrupt signalis output to the print controller 202.

In addition, in the present embodiment, the way the print data read fromthe second buffer is transferred to the print head 8 is explained, butin more detail, the control data including the print data (that is,control data for controlling the print head 8) is transferred to theprint head 8. In the control data, in addition to the print data,various kinds of setting information relating to the printingprocessing, such as information for controlling the ink ejection amount,are included.

Upon receipt of the position counter interrupt signal, the printcontroller 202 performs the clear processing of the interrupt signal forthe position counter 1002. After performing the clear processing of theinterrupt, next, the print controller 202 sets a value corresponding tothe position corresponding to two eighths in the conveyance directionfrom the front end of the image that is printed on a printing sheet tothe register of the position counter 1002 as the position counterinterrupt value. Consequently, in a case where the printing sheet isconveyed up to the position (that is, in a case where the positioncounter value corresponding to the conveyance amount corresponding totwo eighths of the image is reached), a position counter interruptsignal is output to the print controller 202.

Further, the print controller 202 determines that the printingprocessing for the area (1) of the image is completed (that is, theprint data is already transferred to the print head 8) because of thereception of the position counter interrupt signal. That is, byreceiving the position counter interrupt signal, the print controller202 determines (regards) that an empty capacity is produced in thesecond buffer because the area (1) of the print data is transferred tothe print head 8. By receiving the position counter interrupt signal(that is, by determining that an empty capacity is produced in thesecond buffer), the print controller 202 starts processing 2 for thearea (5) stored in the storage area A of the first buffer. Then, in acase where processing 2 is completed, the print controller 202 storesthe generated print data of the area (5) in the second buffer. Asdescribed above, in the present embodiment, processing 2 is started inaccordance with the position counter interrupt signal generated based onthe signal output from the encoder, and therefore, it is not necessaryfor the print controller 202 to check an empty capacity of the secondbuffer.

After this also, the print controller 202 similarly determines that theprint data of the area corresponding to one eighth of the image istransferred to the print head 8 each time of receiving the positioncounter interrupt signal from the position counter 1002 and performs theinterrupt clear processing and processing 2.

Further, in a case of receiving a completion notification (that is,image processing completion interrupt signal) relating to processing 2from the print controller 202, the main controller 101 transfers theareas (7) and (8) of the image whose transfer to the print engine unit200 is not completed yet.

As described above, the transfer processing of image data (that is,processing 1), the image processing (that is, processing 2), and thetransfer processing of print data at the time of the conveyanceoperation of a printing sheet are performed.

As a supplement, by using FIG. 15, the timing at which the positioncounter interrupt signal is output is explained. FIG. 15 is a diagramshowing a position relationship between the print head and image datathat is printed on a printing medium. In FIG. 15, the timing at whichthe first position counter interrupt signal is output in FIG. 10described above is shown.

As shown in FIG. 15, in a case where the printing processing relating toall the colors is completed (that is, at timing at which the printingsheet is conveyed up to the position at which the printing processing iscompleted) in the area corresponding to the area (1) of the image data,the position counter 1002 outputs the position counter interrupt signal.

FIG. 13 is a flowchart showing a procedure of transfer processing ofdata from the controller unit 100 to the print engine unit 200 at thetime of the conveyance operation of a printing sheet. Specifically, FIG.13 is a flowchart showing a procedure of processing 1 for the areas (7)and (8) described above at the time of the conveyance operation of aprinting sheet and the procedure is the same as the procedure ofprocessing 1 for the areas (1) to (6) described above before theconveyance operation of a printing sheet.

At step S1301, the main controller 101 determines whether or not thereis an empty area in the first buffer within the RAM 204. In a case ofdetermining that there is no empty area in the first buffer (No atS1301) the main controller 101 stands by until an empty area is producedin the first buffer. On the other hand, in a case of determining thatthere is an empty area in the first buffer (Yes at S1301), the maincontroller 101 advances the processing to S1302.

At step S1302, the main controller 101 transfers the image datacorresponding to one of the eight areas obtained by equally dividing theimage from the controller unit 100 to the print engine unit 200. Thatis, main controller 101 performs processing 1. At step S1302, each timethe processing at steps S1301 to S1304 in FIG. 13 is performed, the areais shifted from the area (7) to the area (8) to the downstream side inthe conveyance direction and processing 1 is performed.

At step S1303, the main controller 101 determines whether or not thetransfer of the image data transferred from the controller unit 100 atstep S1302 to the print engine unit 200 is completed. That is, the maincontroller 101 determines whether or not processing 1 is completed. In acase of determining that processing 1 is not completed yet (No atS1303), the main controller 101 stands by until processing 1 iscompleted. On the other hand, in a case of determining that processing 1is completed (Yes at S1303), the main controller 101 advances theprocessing to S1304.

At step S1304, the main controller 101 determines whether or notprocessing 1 is completed for the area (7) and the area (8) of theimage. Then, in a case of determining that processing 1 is not completedfor the area (7) and the area (8) of the image (No at S1304), aftershifting the area from the area (7) to the area (8) to the downstreamside in the conveyance direction as described above, the main controller101 returns the processing to step S1301. On the other hand, in a caseof determining that processing 1 is completed for the area (7) and thearea (8) of the image (Yes at S1304), the main controller 101 terminatesthe processing shown in FIG. 13.

FIG. 14 is a flowchart showing a procedure of processing by the printengine unit 200 at the time of the conveyance operation of a printingsheet. Specifically, FIG. 14 is a flowchart showing the conveyanceoperation (printing processing) of a printing sheet for the areas (1) to(8) described above and a procedure of processing 2 for the areas (5) to(8) described above at the time of the conveyance operation of aprinting sheet.

At step S1401, the print controller 202 initializes a variable n forcounting the number of times of position counter interrupt that isoutput from the position counter 1002. That is, the print controller 202sets 0 to the variable n.

At step S1402, a position counter interrupt value is set to the registerwithin the position counter 1002 so that a position counter interruptsignal is output in a case where the printing sheet is conveyed from thefront end of the image up to the position corresponding to one eighth inthe conveyance direction. That is, the position counter interrupt valueis set to the register within the position counter 1002 so that theposition counter interrupt signal is output in a case where the positioncounter value corresponding to the conveyance amount corresponding toone eighth of the image is reached.

At step S1403, the print controller 202 determines whether or not theposition counter interrupt signal is output from the position counter1002. In a case where the position counter interrupt signal is notoutput (No at S1403), the print controller 202 stands by until theposition counter interrupt signal is output and in a case where theposition counter interrupt signal is output (Yes at S1403), the printcontroller 202 advances the processing to step S1404.

At step S1404, the print controller 202 adds 1 to the variable ndescribed above (increments the variable n) because the position counterinterrupt signal is output. At step S1405, the print controller 202performs the clear processing of the interrupt signal for the positioncounter 1002.

At step S1406, the print controller 202 determines whether or not thevariable n is 8, that is, whether or not the position counter interruptsignal is output eight times. In a case of determining that the variablen is not 8 (to be more exact, in a case of determining that the variablen is less than 8) (No at S1406), the print controller 202 advances theprocessing to step S1407.

Next, at step S1407, a position counter interrupt value is set to theregister within the position counter 1002 so that a position counterinterrupt signal is output in a case where the printing sheet isconveyed from the front end of the image up to the positioncorresponding to two eighths in the conveyance direction. That is, theposition counter interrupt value is set to the register within theposition counter 1002 so that the position counter interrupt signal isoutput in a case where the position counter value corresponding to theconveyance amount corresponding to two eighths of the image is reached.

At step S1408, the print controller 202 performs various kinds ofsetting of, for example, such as an image processing parameter and a DMAaddress, for the image processing controller 205. Regarding step S1408,in a case where the processing is performed for the area (5), afterthis, it is not necessarily required to perform the processing and it issufficient to perform the processing appropriately in accordance with achange in environment or the like.

At step S1409, the print controller 202 determines whether or not theimage data for which the transfer from the controller unit 100 to theprint engine unit 200 is completed (that is, image data for whichprocessing 1 is completed) is stored in the first buffer. In a case ofdetermining that the image data is not stored in the first buffer (No atS1409), the print controller 202 stands by until the image data isstored in the first buffer. On the other hand, in a case of determiningthat the image data is stored in the first buffer (Yes at S1409), theprint controller 202 advances the processing to step S1410.

At step S1410, the print controller 202 boots the image processingcontroller 205 and causes the image processing controller 205 to startimage processing. That is, the print controller 202 causes the imageprocessing controller 205 to start processing 2.

After causing the image processing controller 205 to start processing 2,the print controller 202 determines whether or not the interrupt signalrelating to the image processing completion accompanying the completionof processing 2 is received at step S1411. In a case of determining thatthe interrupt signal relating to the image processing completion is notreceived at step S1411 (No at S1411), the print controller 202 stands byuntil the interrupt signal is received. On the other hand, in a case ofdetermining that the interrupt signal relating to the image processingcompletion is received (Yes at S1411), the print controller 202 advancesthe processing to step S1412.

At step S1412, the print controller 202 performs the clear processing ofthe received interrupt signal. Then, after performing the clearprocessing of the interrupt signal, the print controller 202 returns theprocessing to step S1403. After this, the processing is performed untilit is determined that the variable n is 8 at step S1406 and in a casewhere it is determined that the variable n is 8 at step 1406 (that is,in a case where it is determined that the printing operation iscompleted), the processing shown in FIG. 14 is terminated.

Other Embodiments

Embodiment(s) of the present invention can also be realized by acomputer of a system or apparatus that reads out and executes computerexecutable instructions (e.g., one or more programs) recorded on astorage medium (which may also be referred to more fully as a‘non-transitory computer-readable storage medium’) to perform thefunctions of one or more of the above-described embodiment(s) and/orthat includes one or more circuits (e.g., application specificintegrated circuit (ASIC)) for performing the functions of one or moreof the above-described embodiment(s), and by a method performed by thecomputer of the system or apparatus by, for example, reading out andexecuting the computer executable instructions from the storage mediumto perform the functions of one or more of the above-describedembodiment(s) and/or controlling the one or more circuits to perform thefunctions of one or more of the above-described embodiment(s). Thecomputer may comprise one or more processors (e.g., central processingunit (CPU), micro processing unit (MPU)) and may include a network ofseparate computers or separate processors to read out and execute thecomputer executable instructions. The computer executable instructionsmay be provided to the computer, for example, from a network or thestorage medium. The storage medium may include, for example, one or moreof a hard disk, a random-access memory (RAM), a read only memory (ROM),a storage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

In addition, in the embodiments described above, explanation is given bysupposing specifications in which the image that is the target ofprinting processing is divided into eight images and each time theprinting sheet is conveyed by an amount corresponding to one of theeight divided areas (that is, area corresponding to one eighth of theimage), the position counter interrupt signal is output. However, thespecifications in which the position counter interrupt signal is outputare not necessarily limited to those. Consequently, it may also bepossible to output the position counter interrupt signal each time theprinting sheet is conveyed by an amount corresponding to an area otherthan the area corresponding to one eighth of the image (for example,area corresponding to one sixteenth of the image).

Further, explanation is given by supposing that the first buffer has thestructure in which two areas, each corresponding to one eighth of theimage, are included, but as long as the storage capacity of the RAM 204accepts, the number of areas may be more than two. Similarly,explanation is given by supposing that the second buffer also has thestructure in which four areas, each corresponding to one eighth of theimage, are included, but as long as the storage capacity of the RAM 204accepts, the number of areas may be more than four.

Further, as a complement, the capacity of the first buffer is set so asto be smaller than the data size of the image data and the capacity ofthe second buffer is set so as to be smaller than the data size of theprint data converted from the image data.

In addition, the capacity of the first buffer and that of the secondbuffer are set based on the transfer speed (communication speed) of thedata transfer to the print engine unit 200, the conversion speed of theconversion processing from image data into print data, and the transferspeed of the data transfer to the print head 8. Further, the capacityratio between the first buffer and the second buffer is also setsimilarly.

According to the present invention, it is possible to provide an imageforming apparatus capable of simple buffer control in a printingapparatus including a plurality of nozzle rows.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2018-067506, filed Mar. 30, 2018, which is hereby incorporated byreference wherein in its entirety.

What is claimed is:
 1. A printing apparatus comprising: a conveyance unit configured to convey a printing medium in a first direction; an encoder that outputs a predetermined signal in accordance with a drive amount of the conveyance unit, the drive amount corresponding to a conveyance amount of the printing medium in the first direction; a print head having a plurality of nozzles for ejecting ink, with the nozzles arrayed in a second direction intersecting with the first direction; and a print engine connected with the print head and performing conversion processing from image data into print data, wherein the print engine: has a first buffer storing the image data; has a second buffer storing the print data; and converts image data stored in the first buffer into print data in response to a first interrupt signal based on the predetermined signal output from the encoder, and stores the print data in the second buffer, and wherein the print engine further stores another piece of image data not stored in the first buffer in the first buffer in response to a second interrupt signal based on completion of the conversion processing of preceding image data.
 2. The printing apparatus according to claim 1, further comprising: a controller connected with the print engine by a predetermined interface and controlling the print engine, wherein the image data is transferred from the controller to the print engine in response to the second interrupt signal, and the image data is stored in the first buffer.
 3. The printing apparatus according to claim 2, wherein to the first buffer, each piece of image data obtained by dividing image data corresponding to one page into a predetermined number of pieces of image data is transferred from the controller and the print engine performs the conversion processing for each piece of the divided image data and generates divided print data.
 4. The printing apparatus according to claim 3, wherein the controller divides the image data into a predetermined number of pieces of image data in accordance with order of printing an image on the printing medium.
 5. The printing apparatus according to claim 3, wherein a capacity of the first buffer is set so as to be smaller than a data size of image data corresponding to one page and a capacity of the second buffer is set so as to be smaller than a data size of print data corresponding to one page.
 6. The printing apparatus according to claim 3, wherein the print engine outputs the second interrupt signal and starts the conversion processing of next divided image data without checking an empty capacity of the second buffer in a case where the predetermined signal output from the encoder becomes a predetermined counter value.
 7. The printing apparatus according to claim 1, wherein the print engine further performs transfer processing to transfer control data including print data stored in the second buffer to the print head in response to a transfer signal based on the predetermined signal output from the encoder.
 8. The printing apparatus according to claim 7, wherein capacities of the first buffer and the second buffer are set in accordance with a communication speed of the predetermined interface, a conversion speed of converting the image data into the print data, and a transfer speed of transferring the control data to the print head.
 9. A control method of a printing apparatus comprising: a conveyance unit configured to convey a printing medium in a first direction; an encoder that outputs a predetermined signal in accordance with a drive amount of the conveyance unit, the drive amount corresponding to a conveyance amount of the printing medium in the first direction; and a print head having a plurality of nozzles for ejecting ink, with the nozzles arrayed in a second direction intersecting with the first direction, the control method comprising: a step of storing image data in a first buffer; a conversion processing step of converting the image data into print data; and a step of storing the print data in a second buffer, wherein image data stored in the first buffer is converted into print data in response to a first interrupt signal based on the predetermined signal output from the encoder, and the print data is stored in the second buffer, and wherein at the step of storing image data in the first buffer, another piece of image data not stored in the first buffer is stored in the first buffer in response to a second interrupt signal based on completion of the conversion processing of preceding image data.
 10. The control method of a printing apparatus according to claim 9, wherein the image data is transferred from a controller connected by a predetermined interface and stored in the first buffer in response to the second interrupt signal.
 11. The control method of a printing apparatus according to claim 10, wherein to the first buffer, each piece of image data obtained by dividing image data corresponding to one page into a predetermined number of pieces of image data is transferred from the controller and at the conversion processing step, the image data is converted into print data divided for each piece of the divided image data.
 12. The control method of a printing apparatus according to claim 11, wherein the image data corresponding to one page is divided into a predetermined number of pieces of image data in accordance with order of printing an image on the printing medium.
 13. The control method of a printing apparatus according to claim 11, wherein a capacity of the first buffer is set so as to be smaller than a data size of image data corresponding to one page and a capacity of the second buffer is set so as to be smaller than a data size of print data corresponding to one page.
 14. The control method of a printing apparatus according to claim 11, wherein the conversion processing step is a step of outputting the second interrupt signal and converting next divided image data into print data without checking an empty capacity of the second buffer in a case where the predetermined signal output from the encoder becomes a predetermined counter value.
 15. The control method of a printing apparatus according to claim 9, further comprising: a transfer step of transferring control data including print data stored in the second buffer to the print head in response to a transfer signal based on the predetermined signal output from the encoder.
 16. The control method of a printing apparatus according to claim 15, wherein capacities of the first buffer and the second buffer are set in accordance with a communication speed of the predetermined interface, a conversion speed of converting the image data into the print data, and a transfer speed of transferring the control data to the print head.
 17. A printing apparatus comprising: a conveyance unit configured to convey a printing medium in a first direction; an encoder that outputs a predetermined signal in accordance with a drive amount of the conveyance unit, the drive amount corresponding to a conveyance amount of the printing medium in the first direction; a print head having a plurality of nozzles for ejecting ink, which are arrayed in a second direction intersecting with the first direction; and a print engine connected with the print head and performing conversion processing from image data into print data, wherein the print engine: has a first buffer storing the image data; has a second buffer storing the print data; and converts image data stored in the first buffer into print data in response to a first interrupt signal based on the predetermined signal output from the encoder, and stores the print data in the second buffer, the print engine further performs transfer processing to transfer control data including print data stored in the second buffer to the print head in response to a transfer signal based on the predetermined signal output from the encoder. 